Effect of pretreatment on fabrication of natural fibroin fiber/apatite composites using alternate soaking method

To develop biomimetic fibroin/apatite composites with bone-like structure by alternate soaking method, the degummed natural fibroin fibers were pretreated by soaking into CaCl₂:EtOH:H₂O (n(CaCl₂):n(EtOH):n(H₂O)=1:2:8) solution for given time and then soaked into calcium solution and phosphate solution, respectively, to fabricate fibroin/apatite composites. The effects of pretreatment time and the alternate soaking times on fibroin microstructure and fibroin/apatite composites were examined by SEM, FTIR, XRD and TGA techniques. The pretreatment using CaCl₂:EtOH:H₂O (n(CaCl₂):n(EtOH):n(H₂O)=1:2:8) solution makes fibroin fiber exhibit rougher surface and higher internal porosity, which is beneficial to interaction of calcium ion and residue groups such as -COOH, -OH and -CONH- from fibroin, and then improve the deposition of apatite on fibroin fibers. The homogeneous apatites with oriented c-axis were formed on the pretreated fibroin fibers. Moreover, there are more than 30wt% apatites deposited on fibroin fibers after alternate soaking for more than 3 times. The fibroin/apatite composite has potential to be applied as bone repair materials.